Monsanto Co. and DNA Plant Technology Corp. are headed to courtin a battle over patents covering gene marker and promotertechnology used in genetically modifying plants.

Monsanto, of St. Louis, filed a lawsuit in federal court in Delawarealleging infringement of two patents related to the marker andpromoter enabling technologies. DNA Plant Technology countersuedin federal court in Oakland, Calif., claiming the patents are invalidand unenforceable.

Both Monsanto and DNA Plant Technology said Wednesday thelawsuits followed a breakdown in lengthy negotiations on cross-licensing each other's technologies.

Robert Serenbetz, chairman and CEO of DNA Plant Technology,said discussions had been ongoing since the beginning of 1994. Hesaid his company wanted to license Monsanto's marker and promotertechnologies. Monsanto, he added, was interested in DNA PlantTechnology's patented Transwitch gene suppression method.

In genetically altering plants, such as delaying the ripening process oftomatoes, a promoter is used to regulate gene expression and amarker is needed to determine if the genetic transformation wasaccomplished. The transformation, such as suppression of geneexpression, involves another technology.

DNA Plant Technology's Transwitch technique, Serenbetz said, isone method for blocking gene expression. Another is antisensetechnology, which currently is the subject of a patent dispute betweenCalgene Inc., of Davis, Calif., and Enzo Biochem Inc., ofFarmingdale, N.Y.

DNA Plant Technology is in the process of developing new genemarker and promoter technologies, which Serenbetz said shouldrender moot the patent dispute with Monsanto. _ Charles Craig

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